Report discussing tests in a combustion chamber to obtain smoking characteristics data on a variety of hydrocarbon fuels. Details about the smoking tendencies and burning rates of the fuels in uncontrolled and controlled tests are provided.

Report presenting an investigation to determine the effect of the location of the diffuser vanes with respect to the supercharger outlets and the effect of flow conditions at the impeller inlet on the air-flow distribution in the outlets of the engine-stage supercharger of an 18-cylinder double-row radial aircraft engine. The effect of flow conditions at the impeller inlet was investigated by distorting the flow at the inlet and noting the effect in the supercharger outlets. Results regarding the diffuser effect and inlet effect are provided.

From Introduction: "The present report has been prepared to discuss the indications obtained from the University of Chicago turbulence indicator in relation to simultaneous measurement of atmospheric gustiness made by the NACA, which are summarized herein."

Data are presented of the flow conditions in the vicinity of an NACA D sub S -type cowling. Tests were made of a 1/2 scale-nacelle model at inlet-velocity ratios ranging from 0.23 to 1.02 and angles of attack from 6 deg to 10 deg. The velocity and direction of flow in the vertical plane of symmetry of the cowling were determined from orifices and tufts installed on a board aligned with the flow. Diagrams showing velocity ratio contours and lines of constant flow angles are given.

"In the course of an investigation to find a satisfactory vertical tail for the XP-62 airplane, a 0.45-scale vertical tail model on a stub fuselage was tested in the Langley 7- by 10-foot tunnel. This model was fitted with a flat plate to represent the horizontal tail surface. The data are presented herein for their general interest value rather than their application to this particular airplane" (p. 1).

Availability data obtained on SNB-1 trainer-class airplanes were analyzed and results presented as flight envelopes which predict occurrences of large values of air speed and acceleration. Comparison is made with SNJ-4 trainer-class airplane data analyzed by the same method. It is concluded that flight envelopes are satisfactory; that the two types show large differences in flight loads and speeds experience; and that SNB-1 will seldom, if ever, exceed design limit load factor and restricted speed, which SNJ-4 can be expected to exceed design-limit load factor and restricted speed in a very small number of flight hours.

Report discussing testing on 22 inch-diameter pulse-jet engines to determine the effect on performance of a change in combustion-air temperature from approximately 80 degrees to 130 degrees. The effects on jet thrust, combustion-air flow, and engine thrust are described.

Report discussing the effects of various inlet pressures, inlet temperatures, wheel speeds, pressure ratios, and cooling-air flows on the performance of a radial-flow exhaust-gas turbosupercharger turbine with a 12.75-inch tip diameter. Information about efficiency is provided for a given blade-to-jet speed ratio.

"Flight tests of an A-26B airplane have been conducted to determine the changes in maximum speed, as affected by changes in carburetor ram and aerodynamic refinement of the nacelles, resulting from the addition of sealed spinners and modification of the charge air system, cowling, and nacelle afterbodies. The changes in nacelle drag resulting from these modifications were measured independently by means of a revolving wake survey rake behind the nacelle and boundary layer rakes on the cowling, and provide a quantitative check of the speed measurements as well as a means of analyzing the components of nacelle drag" (p. 1).

Results of flight tests of a control-feel aid presented. This device consisted of a spring and dashpot connected in series between the control stick and airplane structure. The device was tested in combination with an experimental elevator and bobweight which had given unsatisfactory dynamic stability and control-feel characteristics in previous tests. The control-feel aid effected marked improvement in both the control-feel characteristics and the control-feel dynamic longitudinal stability of the airplane.

Report discussing the icing characteristics of a rectangular-throat pressure-type carburetor. Serious ice was not found to form under the conditions of this particular test, although visible ice and frost formed in certain areas.

"A preliminary analysis has been made of the conditions of stability of free oscillations of a hinged rotor in hovering flight. The case analyzed is a rotor with hinges allowing freedom in flapping and lagging and having a completely reversible cyclic pitch-control system, so that a twisting moment on a blade moves the control stick without hindrance from spring or friction constraint. The principal results of this study are presented in the form of a stability chart" (p. 1).

From Introduction: "An investigation of the power-plant installation of a single-engine torpedo-bomber-type airplane has been conducted in the NACA Cleveland altitude wind tunnel at the request of the Bureau of Aeronautics, Navy Department. A similar investigation was previously conducted on a three-tenths scale mock-up of the forward portion of the fuselage of this airplane in the Langley 20-foot tunnel. (See reference 1)."

Report presenting the performance of a 22-inch-diameter pulse-jet engine using a net of low-loss modified air valves at ram pressures equivalent to simulated flight speeds. Results regarding combustion-air weight flow, flight thrust, maximum combustion-chamber pressure, specific fuel consumption, pressure cycle, and valve life are provided.

Report discussing the results of accelerated erosion tests to determine the separate effects of the passage of fuel, water, and ice particles through a supercharger. Recommendations for preventing erosion are provided, including materials choice and joint design.

Report discussing measurements of the overall drag coefficient of the XP-51 in dives using three different methods. The three instruments used to measure drag variation are compared for accuracy. A comparison of the drag results obtained from this test are also compared to the results obtained from previous wind tunnel testing.

"Flight tests were conducted on a twin-engine fighter airplane at pressure altitudes up to 10,000 feet with simulated conditions of moderate, heavy, and excessive rain to determine the increase in enthalpy of the charge air due to the turbosupercharger, to determine the rate of enthalpy increase of the charge air resulting from a sudden increase of engine power, and to compare the conditions that caused induction-system icing in flight with those that resulted in icing of the same carburetor and supercharger inlet elbow in laboratory tests" (p. 1).

Report discussing a mock-up injection impeller created to investigate the hydraulic characteristics and limitations of the NACA injection impeller currently in use. Information about the form and magnitude of critical factors of fuel-transfer leakage and peripheral fuel distribution is provided as well as the effects of design variations of components on hydraulic characteristics. Several revisions in portions of the impeller are suggested to improve its fuel-transfer, fuel-pumping, and fuel-equalizing characteristics.

Report discussing several types of jet-exit designs, including normal, beveled, and unsymmetrical shapes, and their effect on the stability characteristics of the aircraft. No deviation of the jet center line from its exposed path is likely to be obtained if a jet exist is used that is normal to the flow. Having a tilted or asymmetrical exit was found to adversely affect the stability of the aircraft.

An investigation was conducted to compare the performance of two 25-ft-diam rotors which had identical dimensions and were similar in construction but different in blade airfoil-sections. Tests were conducted at indicated blade pitch angles from 3 degrees to 11.5 degrees and rotor speeds of 200, 290, and 371 rpm. The 23012.6 rotor required 2 percent less power to hover than the 0012.6. At thrust coefficients above design, the performance of the 23012.6 became better than the 0012.6 rotor.

Report discussing the characteristics of the jet-motor air-intake duct system for a pursuit-type airplane with modifications to the duct system. Details of its effects on the Mach number, high pressure recovery, drag, and simplicity of the system are provided. Problems regarding the flow condition through the ducts and some potential modifications to prevent further issues are also described.

Report discussing the aerodynamic characteristics of a twin-fuselage pursuit airplane model, especially at high speeds. Information about the force data and critical Mach numbers for parts of the model is provided. Suggestions for increasing the Mach number of divergence by making modifications to the wing-fuselage fillets and external shape of the radiator are also included.

"A machined mixed-flow centrifugal impeller of a relatively complex passage shape was used as a pattern to cast a number of aluminum-alloy impellers from two aluminum-base alloys (designated alloys 1 and 2) by the 'lost wax' process. An investigation was conducted to determine whether these cast impellers, could be considered satisfactory for use in compressors. The investigation included preliminary examination, physical tests, metallurgical examination, and performance tests" (p. 1).

Report discussing an investigation of the knock-limited performance of triptane in F-3 and F-4 rating engines, two full-scale air-cooled aircraft cylinders, and flight tests on a full-scale multicylinder engine. Information about the lead susceptibility and effect of engine operating conditions is also provided.